I doubt that any solder resist will prevent dendritic growth. Electro-Chemical Migration (dendrites) requires 3 concurrent conditions: Humidity, Bias and Ionics. 

Solder resists are not impermeable to water / humidity and, with ionic residues underneath, osmotic effects that encourage ECM will become evident in due course. Due course might be hours or months.

Recommend you consider running the new IPC 9202 process characterisation test (include the IPC 9203) to verify the assembly susceptibility to ECM effects then decide.

Hope this helps

Graham Naisbitt
Vice-Chairman IPC SIR, ECM and CAF TC's

Gen3 Systems
www.Gen3systems.com


On 4 Jul 2012, at 17:02, Neil Atkinson wrote:

> 
> 
> What is the view of covering vias with solder resist to prevent dendrite growth?
> 
> This is an FR4 PCB with OSP finish, SMT reflow both sides and a few through hole components soldered with a selective soldering process...
> 
> Thanks in anticipation of the help of the Technet!
> 
> Neil
> 
> 
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